At Ligand Pharmaceuticals, Inc., we investigate novel molecules for their potential as chemotherapeutic and chemopreventive agents. Such molecules are initially identified through numerous in vivo and in vitro assays including a cotransfection assay which measures the functional activity of a compound and competitive binding assays which measure the binding activity of the compounds to specific receptors. In order to further assess biological, pharmacological and stability properties of these novel compounds, it is necessary to prepare high specific activity radiolabelled homologs. The NTLF provides us with the high specific activity tritium gas which is necessary for the synthesis of these compounds.